Currently known sets of doors are of a relatively cumbersome and complex construction. Furthermore, these known sets of doors do not enable a sealed closure to be obtained when the flexible door is in the closed position and said second door is in the open position. In particular, spaces are left, through which insects, an air flow or dust are able to penetrate the enclosure closed off by this set of doors. In practice, it is relatively complicated to make a set of doors which provides satisfactory sealing.
Document U.S. Pat. No. 2,501,454 describes a set of two doors, each of which is wound on a drum to enable them to be opened. An attempt has been made to provide a seal between the wall and the set of these doors by mounting a housing above the bay in which said drums are enclosed. Naturally, mounting such a housing is relatively complex and it is not possible to use such a housing if one of these doors is not wound on a drum. This might be the case, for example, if the second door is a rigid door or a sectional door.